This paper introduces a new method for fingerprint development. This method utilizes sulfur-nitrogen polymer as the developing reagent and employs special development equipment to enhance fingerprints on various metal object surfaces. The sulfur-nitrogen polymer fingerprint development method can achieve the following: the development of latent fingerprints on the surfaces of metal objects; the appearance of latent fingerprints on the surfaces of metal objects after the soaking process; the development of latent fingerprints on the surfaces of metal objects after being washed. In addition, compared with the fingerprint development methods using ‘502’ glue and vacuum deposition systems, the sulfur-nitrogen polymer method offers superior development effects. Research shows that the sulfur-nitrogen polymer method for fingerprint development is effective for latent fingerprinting on metal surfaces. It also has a certain effect on difficult fingerprinting on metal surfaces after treatment involving soaking, detergent washing, and sponge wiping.